The present invention relates generally to a clamping device and more particularly, to sealing rings for electric watt-hour meters.
It is well understood that sealing rings have many applications. They are generally used as clamps for joining or securing cylindrical or annular surfaces. Also, they are particularly used on watt-hour meters that measure the amount of electrical consumption at a particular location, such as a residence or commercial building.
On watt-hour meters, a sealing ring is commonly used to secure the outwardly projecting electrical meter to its meter base. Although each watt-hour meter is secured in a socket in the meter base through frictional and sometimes other means of engagement, sealing rings further prevent the meter from disengaging from its base. Additionally, watt-hour meter sealing rings serve to lock the meter onto its base and prevent unauthorized tampering or removal of the meter. Typically, the meter base which is securely mounted on a wall includes an annular flange. The meter itself has a transparent cover which is provided with a similar flange that is abutted or mated to the flange on the base and they are secured together by the sealing ring.
Commonly, watt-hour meter sealing rings have a split-ring design. Once the meter cover is installed, the sealing ring is wrapped around the mating flanges and secured with a threaded bolt, screw or other fastener. Generally, a screw is used that passes through slots in a pair of tabs that extend outwardly in the radial direction and are located on the ends of the split-ring. By tightening the fastener, the tabs are brought together and the split-ring is fixed firmly to the mating flanges. Additional slots on the tabs are often provided for receiving a key or combination padlock to prevent unauthorized personnel from removing the ring seal. Further, an additional small wire security seal is commonly fixed to the screw and the sealing ring in order to deter and detect tampering.
Installation of sealing rings can be cumbersome and time consuming. Manipulating a screw through the mating tabs, while holding the assembly together, requires some precision under ideal conditions. However, many watt-hour meters are located outdoors, often covered or encroached upon by structures, conduits, cables and surrounding flora, and are difficult to access. Add to this, poor weather conditions, low lighting or uneven terrain and an otherwise relatively simple yet precise task is made difficult.
Another recognized problem is that most watt-hour meter sealing rings come preassembled and require some disassembly before they are installed. In the preassembled configuration the fastener screw is already threaded through both end tabs of the sealing ring (see FIGS. 1 and 2). However, the design of contemporary sealing rings and their fastener screws limit the split-ring aperture, without unthreading the screw from at least one mating tab. Thus, it is virtually impossible to install a contemporary sealing ring on most meters without unscrewing the screw from at least one tab before completing the installation. Thus, the installer is now made to spend additional time and effort, first to disassemble the device, before having to reassemble it for the final installation. Furthermore, upon disassembly, the screw may be dropped and/or lost rendering the device useless.
Also, in an effort to accommodate both left and right handed users, some sealing ring designs allow the fastening screw to be reversed to accommodate their preference. In other words, the screw can be threaded into the tabs from either the left or right side. However, in order to take advantage of this design the user is required to completely disassemble the device by removing the screw from both tabs, before screwing it into the opposite side and completing the reassembly, before the final installation. As discussed above, this can cause difficulties and delays in the final installation.
Yet another recognized problem is that the screw that fastens the split ring tabs is difficult to screw-in because it is positioned in the same central plane as the sealing ring itself, which abuts or is in close proximity to the meter base (See FIGS. 1 and 2). The central plane being defined by a plane in which the longitudinal center of the sealing ring band lies. This position makes it very difficult to engage fingers or tools on the screw in order to tighten it for installation, because the longitudinal axis of the screw, and thus the screw heads, is too close to the meter base.
Similar to the screw position problem discussed above, the wire security seal is also difficult to install in prior art sealing rings. In order to provide a way to secure the fastener screw to the ring seal, slots are frequently machined along the screw's axis. In this way the wire from the security seal is fed from the front of the meter toward the back of the meter through the slot and the sealing ring. However, once again the close proximity of the sealing ring with the meter base makes it difficult for the installer to weave the small security seal wire through these slots from the front toward the back of the meter and then lock into the security seal slug.
Also, traditional sealing ring assemblies use rivets to secure the support tabs to the sealing ring itself. Such rivets can be popped from a fully installed assembly and used to breach the security, which these devices claim to provide. In this way an unauthorized individual can remove the sealing ring assembly without breaking the wire security seal or adjusting the fastener screw.
Additionally, the commonly used screws are difficult to or can not be hand-tightened and often require a specific tool for tightening (as shown by FIG. 1). This causes even more difficulty during installation, as the installer must be equipped and prepared with the correct tool.
Further still, the overall prior art sealing ring designs are difficult to manufacture. The tab support structures are generally the most complex requiring intricate die-cast pieces with numerous detailed cut-outs and bends (see FIGS. 1 and 2). These designs are also difficult for an installer to manipulate or handle in the field. The lack of ergonomic holding positions combined with some sharp edges on the piece can even harm the installer.